Milking equipment employing vacuum milker cups is used extensively in dairy operations in the U.S. Many milking systems include a relatively hard or rigid outer shell within which is mounted a flexible, resilient inflation or liner. Fluctuating pressures are applied to the annular region between the inside of the shell and outer surface of the liner, so as to cause a pulsing, milking motion of the liner. A vacuum is applied to a proximal end of the liner to draw off milk from the tubular region inside the liner. The milk is drawn through tubing to a centralized collecting vessel.
For many years, the inflation or liner has been made of natural or synthetic rubber. In at least one such shell and liner arrangement, the inflation or liner is stretched over a top bead of a teat cup shell, pulled through the shell and turned up at the proximal end which has a reduced diameter neck and bead. The turned up liner is held in place by the expanded head of a milk tube. Conventional teat cup assemblies with liners upturned at their proximal ends are illustrated in U.S. Pat. Nos. 1,239,923; 1,959,581; 2,061,809; 2,219,945; 2,300,833 and 2,323,851.
Inflations or liners made of silicone rather than natural or synthetic rubber have a number of advantages. Silicone inflations or liners do not absorb butter fat and oils or moisture as do rubber liners. Silicone inflations resist extremes of temperatures, are flexible even at low temperatures and resist deterioration due to sunlight, oils, solids and other chemicals and can be used for extensive periods of time. One arrangement for using a silicone inflation or liner in the milking teat cup shell is disclosed in U.S. Pat. No. 4,651,676. The patent is directed to an improved shell involving an enlarged and extended cylindrical shell wall for protecting the distal end of the silicone liner.
Nevertheless, silicone liners must be replaced periodically. One effective system for making this replacement is to replace the entire liner and shell unit with a new liner and shell unit. It is contemplated that the replacement unit will have been properly assembled and tested for effectiveness before it is acquired and installed by the milking system operator.
Accordingly, it is an object of this invention to provide a teat cup assembly including a silicone inflation or liner that can be easily assembled into the shell so as to effectively and reliably maintain the necessary end fluid-tight seal between the inflation and the shell.
Another object is to provide a shell-inflation attachment and seal arrangement which will seal effectively for a long time.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings. Throughout the drawings, like reference numerals refer to like parts.